A virtual universe (VU) is an interactive simulated environment accessed by multiple users through an online interface. Users inhabit and interact in the VU via avatars, which are a user's representation of himself or herself. These representations can be in the form of a three-dimensional model, a two-dimensional icon, a text construct, a user screen name, etc. Although there are many different types of VUs, there are several features many VUs generally have in common. These features include, for example,                Shared Space: the VU allows many users to participate at once;        Graphical User Interface: the VU depicts space visually, ranging in style from 2D “cartoon” imagery to more immersive 3D environments;        Immediacy: interaction takes place in real time;        Interactivity: the VU allows users to alter, develop, build, or submit customized content;        Persistence: the VU's existence continues regardless of whether individual users are logged in; and        Socialization/Community: the VU allows and encourages the formation of social groups such as teams, guilds, clubs, cliques, housemates, neighborhoods, etc.        
Visual clues as to a person's emotions, state of mind, state of health, etc., are important in helping people fully understand the context of a communication, both in the real world and in a VU. For example, direct and indirect clues, such as facial expressions, subtle body movements and postures, eye jitter, clothing, gestures, and even changes in skin coloration due to emotion, can be used to determine whether a user is nervous, tired, annoyed, sick, etc. In the real world, these types of subtle queues assist communication, facilitate empathy, and shape our social and business interactions. However, these subtleties are not conveniently reflected in virtual universes.
For example, if a user wanted to smile in a VU, the user would have to manually issue a command to make the user's avatar smile. This command would have to be issued over and over to denote that the avatar was happy. Understandably, this detracts from the immersive characteristic of a VU, is time consuming, and distracting. Moreover, since the command lasts only for a very short period of time, avatars may not pick up on the visual clue and may misinterpret textual and/or audio communications that would have otherwise been obvious if the users were interacting face to face in the real world.